CHAPTER SEVEN Stereochemistry An elaborate network connecting signs of rotation and relative configurations was developed that included the most important compounds of organic and biological chemist When, in 1951, the absolute configuration of a salt of (+)-tartaric acid was determined, the absolute configurations of all the compounds whose configurations had been related to (+)-tartaric acid stood revealed as well. Thus, returning to the pair of 2-butanol enantiomers that introduced this section, their absolute configurations are now known to be as shown CHaO CHCH OH CH (+)-2-Butano (一)2- Butanol PROBLEM 7.6 Does the molecular model shown represent (+)-2-butanol or ()-2-butanol? 7.6 THE CAHN-INGOLD-PRELOG R-S NOTATIONAL SYSTEM Just as it makes sense to have a nomenclature system by which we can specify the con stitution of a molecule in words rather than pictures, so too is it helpful to have one that lets us describe stereochemistry. We have already had some experience with this idea when we distinguished between E and Z stereoisomers of alkenes. In the E-Z system, substituents are ranked by atomic number according to a set of rules devised by R. S. Cahn, Sir Christopher Ingold, and Vladimir Prelog(Section 5.4) Actually, Cahn, Ingold, and Prelog first developed their ranking system to deal with the problem of the absolute configuration at a stereogenic center, and this is the systems major application. Table 7.1 shows how the Cahn-Ingold-Prelog system, called the sequence rules, is used to specify the absolute configuration at the stereogenic center in(+)-2-butanol The January 1994 issue of As outlined in Table 7.1,(+)-2-butanol has the S configuration. Its mirror image is(-)-2-butanol, which has the R configuration cation contains an article that describes how to your hands to assign R and S configurations. CH: CH H H CH,CH3 -OH Ho-C CH (S)-2-Butane (R)-2-Butano Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsiteAn elaborate network connecting signs of rotation and relative configurations was developed that included the most important compounds of organic and biological chemistry. When, in 1951, the absolute configuration of a salt of ()-tartaric acid was determined, the absolute configurations of all the compounds whose configurations had been related to ()-tartaric acid stood revealed as well. Thus, returning to the pair of 2-butanol enantiomers that introduced this section, their absolute configurations are now known to be as shown. PROBLEM 7.6 Does the molecular model shown represent ()-2-butanol or ()-2-butanol? 7.6 THE CAHN–INGOLD–PRELOG R–S NOTATIONAL SYSTEM Just as it makes sense to have a nomenclature system by which we can specify the con￾stitution of a molecule in words rather than pictures, so too is it helpful to have one that lets us describe stereochemistry. We have already had some experience with this idea when we distinguished between E and Z stereoisomers of alkenes. In the E–Z system, substituents are ranked by atomic number according to a set of rules devised by R. S. Cahn, Sir Christopher Ingold, and Vladimir Prelog (Section 5.4). Actually, Cahn, Ingold, and Prelog first developed their ranking system to deal with the problem of the absolute configuration at a stereogenic center, and this is the system’s major application. Table 7.1 shows how the Cahn–Ingold–Prelog system, called the sequence rules, is used to specify the absolute configuration at the stereogenic center in ()-2-butanol. As outlined in Table 7.1, ()-2-butanol has the S configuration. Its mirror image is ()-2-butanol, which has the R configuration. C H H3C CH3CH2 OH (S)-2-Butanol H CH3 CH2CH3 HO C (R)-2-Butanol and C H H3C CH3CH2 OH H CH3 CH2CH3 HO C ()-2-Butanol ()-2-Butanol 268 CHAPTER SEVEN Stereochemistry The January 1994 issue of the Journal of Chemical Edu￾cation contains an article that describes how to use your hands to assign R and S configurations. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website